Most of the studies of boiling heat transfer to an impinged jet have paid attention only to the area near the stagnation region. However, in the case of cooling a massive body by a jet, heat transfer outside the stagnation region and temperature profile inside the body are important, as well. In this paper, transient boiling heat transfer rate to a two dimensional impinged water jet was measured at each point on the whole surface of a 20×150 mm rectangle, during cooling from about 400°C to 100°C. Local surface temperature fell rapidly when the temperature at that point reached the temperature corresponding to its high heat flux region of transition boiling. The rapid cooling line on the surface progressed from the impinging region toward the outer ends of the surface, in accordance with the progress of boiling peak heat flux line. Temperature profiles inside the body were also calculated at respective times with the measured transient surface heat flux distribution as the boundary condition. Cooling rate was very sensitive to the jet impinging velocity.
